Computer Aided Design and Drafting (CADD) has become a standard design tool for manipulating and recording design information in many industries, including the manufacturing and construction industries. In this way, design information, such as for a manufactured product or a construction project, is transformed into a computerized model. CADD models are accurate depictions of the position, shape and orientation of the objects composing the design, and their relationship to each other and the environment in which they are contained.
Beliveau et al, U.S. patent application Ser. No. 07/570,268, filed Aug. 17 1990, now U.S. Pat. No. 5,100,229 and Dornbusch et al U.S. patent application No. 07/636,459, filed Dec. 31, 1990, now U.S. Pat. No. 5,110,202 the contents of which are incorporated herein by reference, describes a system and method in which a CADD model is used in conjunction with a portable position sensor and a plurality of reference stations to position distinguished points in an environment. In the system and method disclosed by Beliveau et al., actual position and orientation information of a vehicle, for example, can be transmitted back to the computer and compared to the desired position of the vehicle in the CADD model, and then the position of the vehicle can be automatically corrected if necessary.
Unfortunately, a finished environment often differs from its design, due to problems such as errors in design and tolerance capability. Thus, there is a difficulty that the CADD model no longer accurately represents the environment constructed therefrom. CADD models could be used to record the "as-built" or "as-is" position, shape and orientation data of the components of an environment, for example, an existing manufactured product or industrial facility, if these data could be determined.